docs: def in6_get6to4Prefix(addr):
      """
      Returns the /48 6to4 prefix associated with provided IPv4 address
      On error, None is returned. No check is performed on public/private
      status of the address
      """
      try:
          addr = inet_pton(socket.AF_INET, addr)
          addr = inet_ntop(socket.AF_INET6, b'\x20\x02'+addr+b'\x00'*10)
      except:
          return None
      return addr